A new political row broke out in the French presidential election race yesterday as it emerged that the two leading candidates have sharply differing views on how to deal with the growing problem of racism.

For months, both the Socialist Ségolène Royal and the rightwing interior minister, Nicolas Sarkozy, have been considering whether to break one of France's biggest taboos and begin officially counting the number of people belonging to ethnic minorities in France. Classifying people by their ethnicity is illegal in France - the nation of "liberty, equality, fraternity" considers all people should be equally French with no differentiation. Unlike in Britain, no direct census questions can be asked that would determine the exact ethnic, racial or religious makeup of society. Without statistics, some minority groups argue that racism and discrimination are being swept under the carpet.

France's umbrella organisation for black groups, Cran, this week repeated demands that France begin collecting statistics. It polled the candidates' views and found Mr Sarkozy was in favour of counting ethnic groups, along with several other candidates. Ms Royal was the only one against.

Patrick Lozès, head of Cran, told the Guardian: "The fact that most candidates are in favour of collecting these statistics is a sea change in France. Three years ago this was completely taboo. Ségolène Royal was clear about her reasons for opposing it: she feared information could be used to keep records on individuals."

The poll prompted 40 academics and campaigners to publish a petition in yesterday's daily Libération in protest at "ethnic statistics", warning they could lead to "confrontation" between groups.

Race is a key election issue as non-white people complain of unfair stop-and-searches by heavy-handed police, and many say they are excluded from housing and employment. Community workers on run-down, ethnically mixed housing estates warn nothing has been done to stop racist discrimination despite the worst riots in nearly 40 years in 2005.

Non-white graduates with top-class degrees complain that CVs go unanswered because of the colour of their skin or non-French surname. The government has since moved to ban the requirement for a photo on CV applications, introducing the principle of "anonymous CVs" but the law has not yet come into effect.

This month, the umbrella group for black associations published the first opinion poll in France asking people about race.

In all, 56% of black people said they suffered racial discrimination in their everyday lives, and 37% said the discrimination had got worse in the past year. Louis-Georges Tin, the group's spokesman said "Being black [in France] is a social handicap."

Mr Sarkozy, known for his tough stance on immigration, has recently been engaged in a slanging match over race with the black French footballer Lilian Thuram. The player has repeatedly said Mr Sarkozy told him after the 2005 riots: "It's the blacks and Arabs who create problems in the suburbs." Mr Sarkozy has denied racism, hiring another footballer to advise him on diversity.

Ms Royal has said she wants to be president of a "mixed-race" France, proposing anti-racism measures such as forcing companies to reassess their recruitment policies. But last month the Socialist party was forced to expel one of its leading members - Gêorges Freche, president of the Languedoc-Roussillon region - who complained there were too many black players in the French national football team.